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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-326) The lowest level map-reduce APIs should be byte oriented
Date Sat, 13 Feb 2010 03:27:28 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833304#action_12833304
] 

Chris Douglas commented on MAPREDUCE-326:
-----------------------------------------

@Chris Dyer

The current proposal explicitly avoids taking a position on the non-Java use case. Better
pipes/streaming workflows are explicitly considered in MAPREDUCE-1183; one can imagine an
implementation of the MapTask or ReduceTask loading its user code in an implementation written
in the native language. While pulling out the utility classes, I'm hoping we can also work
toward standardizing the intermediate formats that would make such native implementations
possible, incrementally. That said, the existing inefficiencies in the pipes/streaming APIs
can be ameliorated without any progress on these issues. As you point out, the implementation
is not optimized and would benefit from a determined refactoring.

> The lowest level map-reduce APIs should be byte oriented
> --------------------------------------------------------
>
>                 Key: MAPREDUCE-326
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-326
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>            Reporter: eric baldeschwieler
>         Attachments: MAPREDUCE-326-api.patch, MAPREDUCE-326.pdf
>
>
> As discussed here:
> https://issues.apache.org/jira/browse/HADOOP-1986#action_12551237
> The templates, serializers and other complexities that allow map-reduce to use arbitrary
types complicate the design and lead to lots of object creates and other overhead that a byte
oriented design would not suffer.  I believe the lowest level implementation of hadoop map-reduce
should have byte string oriented APIs (for keys and values).  This API would be more performant,
simpler and more easily cross language.
> The existing API could be maintained as a thin layer on top of the leaner API.

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